title: Activation of the Wnt pathway through AR79, a GSK3β inhibitor, promotes prostate cancer growth in soft tissue and bone.
abstract: Due to its bone anabolic activity, methods to increase Wnt activity, such as inhibitors of dickkopf-1 and sclerostin, are being clinically explored. Glycogen synthase kinase (GSK3β) inhibits Wnt signaling by inducing β-catenin degradation, and a GSK3β inhibitor, AR79, is being evaluated as an osteoanabolic agent. However, Wnt activation has the potential to promote tumor growth; therefore, the goal of this study was to determine if AR79 has an impact on the progression of prostate cancer. Prostate cancer tumors were established in subcutaneous and bone sites of mice followed by AR79 administration, and tumor growth, β-catenin activation, proliferation, and apoptosis were assessed. Additionally, prostate cancer and osteoblast cell lines were treated with AR79, and β-catenin status, proliferation (with β-catenin knockdown in some cases), and proportion of ALDH(+)CD133(+) stem-like cells were determined. AR79 promoted prostate cancer tumor growth, decreased phospho-β-catenin, increased total and nuclear β-catenin, and increased tumor-induced bone remodeling. Additionally, AR79 treatment decreased caspase-3 and increased Ki67 expression in tumors and increased bone formation in normal mouse tibiae. Similarly, AR79 inhibited β-catenin phosphorylation, increased nuclear β-catenin accumulation in prostate cancer and osteoblast cell lines, and increased proliferation of prostate cancer cells in vitro through β-catenin. Furthermore, AR79 increased the ALDH(+)CD133(+) cancer stem cell-like proportion of the prostate cancer cell lines. In conclusion, AR79, while being bone anabolic, promotes prostate cancer cell growth through Wnt pathway activation.
  
  
  CONCLUSIONS
  These data suggest that clinical application of pharmaceuticals that promote Wnt pathway activation should be used with caution as they may enhance tumor growth.
authors.affiliation: Department of Urology, University of Michigan, 5308 CCGC, 1500 E. Medical Center Drive, Ann Arbor, MI 48109-8940. etkeller@umich.edu.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Jiang
authors.forename: Jinlu
authors.initials: J
authors.lastname: Dai
authors.forename: Honglai
authors.initials: H
authors.lastname: Zhang
authors.forename: Joe L
authors.initials: JL
authors.lastname: Sottnik
authors.forename: Jill M
authors.initials: JM
authors.lastname: Keller
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Escott
authors.forename: Hitesh J
authors.initials: HJ
authors.lastname: Sanganee
authors.forename: Zhi
authors.initials: Z
authors.lastname: Yao
authors.forename: Laurie K
authors.initials: LK
authors.lastname: McCauley
authors.forename: Evan T
authors.initials: ET
authors.lastname: Keller
mesh_terms: D045930:Anabolic Agents / Q000494:pharmacology*; D000818:Animals; D001859:Bone Neoplasms / Q000378:metabolism / Q000473:pathology / Q000556:secondary*; D045744:Cell Line, Tumor; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009374:Neoplasms, Experimental; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D012983:Soft Tissue Neoplasms / Q000378:metabolism / Q000473:pathology / Q000556:secondary*; D013977:Tibia; D060449:Wnt Signaling Pathway / Q000187:drug effects* / Q000235:genetics; D051176:beta Catenin / Q000378:metabolism
chemical_list: D045930:Anabolic Agents; D047428:Protein Kinase Inhibitors; D051176:beta Catenin; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3